The two-week experiment - taking place in the Western Austrian Alps - was trying to determine what factors make it possible for humans to survive an avalanche in an air pocket until rescued without suffering permanent brain damage.

Hermann Brugger, co-director of the experiment led by the Institute of Mountain Emergency Medicine in Bolzano, Italy, and the Medical University of Innsbruck, Austria, asserted the pigs didn't suffer because they were sedated and given an anesthetic beforehand.

But activists called it cruel and pointless.

Following protests Thursday, Herbert Lochs, director of the Medical University of Innsbruck, confirmed the experiment had been halted temporarily due to the massive media interest sparked by the activists' protests. A total of 29 animals had been selected for the tests.

"It is absolutely unacceptable that these highly sensitive, helpless animals are killed for such an unnecessary test," said Johanna Stadler, head of the group Four Paws.

"People are shocked and outraged that such cruel experiments can even be carried out in Austria," said Gerda Matias, president of the International Union of Animal Experiment Opponents.

In a statement posted on the Medical University of Innsbruck's Web site, organizers said the experiment was ethically justifiable and had been approved by a commission in Austria's Science and Research Ministry.

Brugger, in a telephone interview with The Associated Press, said the study could help humans survive an avalanche and that stopping now would mean that those pigs that already died did so in vain.

"We want to save lives, that's the only goal of this study," he said in an interview with Austrian broadcaster ORF.